The use of radiation to treat medical conditions comprises a known area of prior art endeavor. For example, radiation therapy comprises an important component of many treatment plans for reducing or eliminating unwanted tumors. Unfortunately, applied radiation does not inherently discriminate between unwanted areas and adjacent healthy tissues, organs, or the like that are desired or even critical to continued survival of the patient. As a result, radiation is ordinarily applied in a carefully administered manner to at least attempt to restrict the radiation to a given target volume.
Treatment plans typically serve to specify any number of operating parameters as pertain to the administration of such treatment with respect to a given patient. Such treatment plans are often optimized prior to use. (As used herein, “optimization” will be understood to refer to improving upon a candidate treatment plan without necessarily ensuring that the optimized result is, in fact, the singular best solution.) Many optimization approaches use an automated incremental methodology where various optimization results are calculated and tested in turn using a variety of automatically-modified (i.e., “incremented”) treatment plan optimization parameters.
Generally speaking, a well-conceived radiation-treatment plan serves to help ensure that the treatment target receives a prescribed dose of radiation while avoiding, to as large an extent as might be possible, undue dosing of surrounding or intervening tissues and organs. Unfortunately, the therapeutic radiation being used to so treat the patient is often not the only source of radiation dosing in a modern treatment facility.
For example, as part of ensuring that the therapeutic radiation beam is properly administered it can be very important to be certain of the patient's position and orientation. Even the most carefully conceived radiation-treatment plan can be rendered less effective if the patient's treatment volume moves or otherwise changes in unanticipated ways. Accordingly, images of the patient that are formed using megavoltage energies are becoming more common as such images provide helpful information regarding such positioning.
That image-forming energy, however, is radiation that may be over and above whatever carefully determined dosing is anticipated by the radiation-treatment plan. In some cases the administering technicians or other medical services providers attempt to manually account for such incidental radiation when managing the formation of their radiation-treatment plans. In other cases the issue simply goes unaddressed.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present teachings. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present teachings. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.